摘要
采用溶胶-凝胶法制备了(Pr_(1-x)La_x)_(0．75)Na_(0．25)MnPO_3(0．00≤x≤1．00)系列多晶样品．X射线衍射结果表明．所有样品均为单相类钙钛矿结构,随着La^(3+)离子含量的增加,样品由x≤0．50时的正交结构转变为x≥0．70时的菱面体结构．磁性测量结果表明,La^(3+)离子的掺入还导致了Pr_(0．75)Na_(0．25)MnO_3电荷有序的破坏．在x≤0．1时,电荷有序转变温度随La^(3+)离子含量增加而降低；当x＞0．10时,电荷有序现象消失,样品出现顺磁-铁磁相变,同时伴随着绝缘体-金属转变．磁熵变研究表明,x≥0．5的样品在室温附近和较低磁场下具有较大的磁熵变,可望成为新的室温磁致冷材料．
Polycrystalline （Pr1-xLax）0.75Na0.25MnO3（0.00 ≤ x ≤ 1.00） manganites were prepared by sol-gel method. X-ray Diffraction patterns showed that the samples are crystallized in single phase with perovskite-like structure. The structure of the compounds transforms from orthorhombic structure for x≤0.50 to rhombohedral structure for x ≥0.70. The introduction of La^3＋ ions also suppresses the charge ordering in the samples. The charge ordering transition temperature decreases with increasing La^3＋ doping when x ≤0.10. The charge ordering phenomenon disappeared for the samples with x 〉 0.10, paramagnetic-ferromagnetic transition appeared, while the insulator-metal transition can be observed. For x≥0.50, the compounds also show large magnetic entropy change under low field near or above room temperature, indicating the material can he used in magnetic refrigeration.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第9期974-978,共5页
Acta Metallurgica Sinica
基金
国家自然科学基金项目10504024
天津市自然科学基金项目043602111资助
关键词
锰氧化物
庞磁电阻
电荷有序
相分离
磁熵变
manganite, colossal magnetoresistance, charge ordering, phase separation, magnetic entropy change
